Characterization of Emissions of Volatile Organic Compounds from Interior Alkyd Paint

ABSTRACT

Alkyd paint continues to be used indoors for application to wood trim, cabinet surfaces, and some kitchen and bathroom walls. Alkyd paint may represent a significant source of volatile organic compounds (VOCs) indoors because of the frequency of use and amount of surface painted. The U.S. Environmental Protection Agency (EPA) is conducting research to characterize VOC emissions from paint and to develop source emission models that can be used for exposure assessment and risk management. The technical approach for this research involves both analysis of the liquid paint to identify and quantify the VOC contents and dynamic small chamber emissions tests to characterize the VOC emissions after application. The predominant constituents of the primer and two alkyd paints selected for testing were straight-chain alkanes (C9–C12); C8–C9 aromatics were minor constituents. Branched chain alkanes were the predominant VOCs in a third paint. A series of tests were performed to evaluate factors that may affect emissions following application of the coatings. The type of substrate (glass, wallboard, or pine board) did not have a substantial impact on the emissions with respect to peak concentrations, the emissions profile, or the amount of VOC mass emitted from the paint. Peak concentrations of total volatile organic compounds (TVOCs) as high as 10,000 mg/m³ were measured during small chamber emissions tests at 0.5 air exchanges per hour (ACH). Over 90% of the VOCs were emitted from the primer and paints during the first 10 hr following application. Emissions were similar from paint applied to bare pine board, a primed board, or a board previously painted with the same paint. The impact of other variables, including film thickness, air velocity at the surface, and air-exchange rate (AER) were consistent with theoretical predictions for gas-phase, mass transfer-controlled emissions. In addition to the alkanes and aromatics, aldehydes were detected in the emissions during paint drying. Hexanal, the predominant aldehyde in the emissions, was not detected in the liquid paint and was apparently an oxidation product formed during drying. This paper summarizes the results of the product analyses and a series of small chamber emissions tests. It also describes the use of a mass balance approach to evaluate the impact of test variables and to assess the quality of the emissions data.     

Modeling the Reduction of Vapor Phase Emissions from Surface Soils Due to Soil Matrix Effects: Porosity/Tortuosity Concepts

ABSTRACT

A major route for transport of volatile organic compounds within porous media is vapor phase diffusion. The diffusion rate through a porous medium is less than that through free-air due to the decreased cross-sectional area available for gas movement and the increased path length due to pore tortuosity. Numerous empirical expressions have been published that relate the diffusion coefficient in porous media to the diffusion coefficient in free-air (unobstructed gas phase). Published measurements of relative diffusivity and air-filled porosity were combined into a database. Empirical expressions available in the literature, including the popular Millington-Quirk equation, were evaluated along with a fourth-degree polynomial expression developed by the authors to determine the best type of equation to predict relative diffusivity as a function of air-filled porosity over the domain of values for porosity ranging from 0.071 to 1 for different types of materials. Mean square deviations were used as the statistical test to compare equations. The polynomial expression developed in this project produced a significantly different effective diffusion coefficient (1.3 x 10^-6 m²/sec) compared to values of 9.2 x 10^-6 m²/sec and 3.1 x 10^-6 m²/ sec predicted by forms of the Millington-Quirk equation for a specific case.     

Estimating Fugitive Emissions of Volatile Compounds from Equipment Leaks

This paper is directed to those concerned with estimating releases to the air of volatile compounds from equipment component leaks. We compared emission rates for equipment component leaks using EPA’s Average Emission Factor Method, Leak/No-Leak Emission Factor Method, and Stratified Emission Factor Method. The latter two methods may be used if there are concentration measurements about the components. An organic vapor analyzer was applied with the appropriate response factor to measure the concentrations around each equipment component using EPA Method 21. We analyzed this data to determine mass emission rates. Results show that the Average Emission Factor Method substantially overstates the emission rates calculated using these other two methods. We conclude that use of Method 21 concentration measurements with the Leak/No Leak or Stratified Emission Factor Method may increase the accuracy and reduce significantly the estimated releases to the air of volatile compounds from equipment component leaks for many facilities.     

Biofiltration of a Mixture of Volatile Organic Emissions

ABSTRACT

Air biofiltration is now under active consideration for the removal of the volatile organic compounds (VOCs) from polluted airstreams. To optimize this emerging environmental technology and to understand compound removal mechanisms, a biofilter packed with peat was developed to treat a complex mixture of VOCs: oxygenated, aromatic, and chlorinated compounds. The removal efficiency of this process was high. The maximum elimination capacity (ECmax) obtained was ~120 g VOCs/m³ peat/hr. Referring to each of the mixture's components, the ECmax showed the limits in terms of biodegradability of VOCs, especially for the halogenated compounds and xylene.

A stratification of biodegradation was observed in the reactor. The oxygenated compounds were metabolized before the aromatic and halogenated ones. Two assumptions are suggested. There was a competition between bacterial communities. Different communities colonized the peat-based biofilter, one specialized for the elimination of oxygenated compounds, the others more specialized for elimination of aromatic and halogenated compounds. There was also substrate competition. Bacterial communities were the same over the height of the column, but the more easily biodegradable compounds were used first for the microorganism metabolism when they were present in the gaseous effluent.     

Microwave Plasma Conversion of Volatile Organic Compounds

Abstract

A microwave-induced, steam/Ar/O₂ , plasma “torch” was operated at atmospheric pressure to determine the feasibility of destroying volatile organic compounds (VOCs) of concern. The plasma process can be coupled with adsorbent technology by providing steam as the fluid carrier for desorbing the VOCs from an adsorbent. Hence, N₂ can be excluded by using a relatively inexpensive carrier gas, and thermal formation of oxides of nitrogen (NO_x ) is avoided in the plasma.

The objectives of the study were to evaluate the technical feasibility of destroying VOCs from gas streams by using a commercially available microwave plasma torch and to examine whether significant byproducts were produced. Trichloroethene (TCE) and toluene (TOL) were added as representative VOCs of interest to a flow that contained Ar as a carrier gas in addition to O₂ and steam.The O₂ was necessary to ensure that undesirable byproducts were not formed in the process. Microwave power applied at 500–600 W was found to be sufficient to achieve the destruction of the test compounds, down to the detection limits of the gas chromatograph that was used in the analysis. Samples of the postmicrowave gases were collected on sorbent tubes for the analysis of dioxins and other byproducts. No hazardous byproducts were detected when sufficient O₂ was added to the flow. The destruction efficiency at a fixed microwave power improved with the addition of steam to the flow that passed through the torch.     

Nitrous Oxide Emissions from Drained,Cultivated Organic Soils of South Florida

Due to the intense microbial oxidation of organic soils in the Florida Everglades, approximately 1400 kg N/ha are mineralized annually. Most of this nitrogen is lost to the atmosphere through denitrification in the soil. Nitrous oxide is one of the gaseous products of denitrification, therefore the objectives of this study were to determine the quantities of N₂O emitted from these soils and to measure the effect of this N₂O on ambient mixing ratios in the Everglades. Nitrous oxide fluxes from these soils ranged from 4 g N/ha/day, during dry periods, to 4500 g N/ha/day following rainfall events. Nitrous oxide emissions increased with increasing soil moisture. From April through the end of December 1979, a total of 165, 97, and 48 kg N₂O-N/ha were emitted from fallow, St. Augustine grass, and sugarcane fields, respectively. There was a diurnal variation in the N2O mixing ratios of air 8 m above the soil in the Everglades. This diurnal fluctuation was affected by wind speed. There was a significant linear correlation between the average daily mixing ratio and the flux of N₂O from the soil.     

生活垃圾填埋场填埋气中挥发性有机物释放规律分析

于2007年2月在上海老港垃圾填埋场选取10个不同填满年限的填埋单元进行填埋气的采样分析,用色谱-质谱技术检测了填埋气中的挥发性有机物(VOCs).检测到脂肪烃、卤代脂肪烃、单环芳烃、醚和酮等5类22种化合物,其中11种为美国环境保护署优先控制污染物,甲苯、乙苯和间,对二甲苯的浓度较高.填满时间距采样时间较近(1～2年)的填埋单元检出的VOCs种类较多,脂肪烃和单环芳烃的浓度随填满时间的增加呈现较明显的衰减特征,而卤代脂肪烃、醚和酮的浓度与填满时间的相关性不显著.检出的5种化合物中,1,1,1三氯乙烷、甲苯和间,对-二甲苯的浓度均低于美国加利福尼亚州环保局推荐的健康阈值,氯乙烯和苯则超过该阈值.     

Evaluation of Canisters for Measuring Emissions of Volatile Organic Air Pollutants from Hazardous Waste Incineration

Regulation to control air emissions of toxic organic compounds require the collection and analysis of effluent gas from low level sources such as hazardous waste incinerators. The standard SW- 846 Method specifies the use of Tenax and Tenax/charcoal adsorbent traps for collection of volatile organics from incinerators. This study evaluates passivated stainless steel canisters as an alternative to adsorbent traps to eliminate some of the problems associated with adsorbent sampling. Initially the stability of 18 nonpolar, volatile organic compounds was determined in Summa-treated stainless steel canisters with greater than 100 ppmv HCI and saturated with water vapor. All 18 components were stable for a twoweek period; however, an Interference caused a 10-fold increase In the FID response of trlchloroethylene, toluene, and chlorobenzene. No Interference of the ECD response was found for any of the 11 compounds detected with the ECD including trlchloroethylene. A pilot scale incinerator was sampled using canisters, and the destruction efficiency of 1,1,1-trichloroethane was determined at a concentration of less than 0.5 ppbv while determining 1,1-dichloroethylene, the major product of Incomplete combustion, at a concentration of 8000 ppbv from the same sample.     

Characterization of Volatile Organic Chemical Emissions From Carpet Cushions

Abstract

The U.S. Consumer Product Safety Commission is investigating chemical emissions from carpet systems in order to determine whether the emissions may be responsible for the numerous health complaints associated with carpet installation. As part of this effort, a study was conducted to identify and quantify volatile organic compounds (VOCs) released into the air by five major product types of new carpet cushions. Cushion samples were tested in small-volume dynamic chambers over a six-hour exposure period. Airborne VOCs collected on multisorbent samplers were identified using sensitive gas chromatography/mass spectrometry. The emissions of selected VOCs were quantitated with the small-scale chamber method and further characterized in larger environmental chambers conducted over a 96-hour period under conditions more representative of indoor environments. A separate chamber method was developed to screen polyurethane cushions for emissions of toluene diisocyanates (TDI). Over 100 VOCs, spanning a broad range of chemical classes, were emitted from 17 carpet cushions. The pattern of emitted VOCs varied between and among product types, which reflects probable differences in manufacturing processes and ingredients. No significant quantities of TDI or formaldehyde were released by any cushions. Emission profiles were characterized for total VOCs and for the predominant individual VOCs. As a group, the synthetic fiber cushion samples emitted the lowest quantities of VOCs. Cushion samples purchased from carpet retailers released lesser amounts of VOCs than samples of the same cushion types obtained directly from the manufacturing mills, suggesting that chemical losses from the bulk material may ensue as a result of transport, handling, and storage prior to installation. The data suggest that placement of carpet on top of a carpet cushion, as would occur in a residential installation, reduced the rate of some VOC emissions when compared to the cushion alone.     

Destruction of Volatile Organic Compounds Using Catalytic Oxidation

Catalytic oxidation is an air pollution control technique in which volatile organic compounds (VOCs) and vapor-phase air toxics in an air emission stream are oxidized with the help of a catalyst Design of catalytic systems for control of point source emissions is based on stream-specific characteristics and desired control efficiency. This paper discusses the key emission stream characteristics and VOC characteristics that affect the applicability of catalytic oxidation. The application of catalytic oxidation technology to four types of air emission sources is discussed: (1) groundwater stripping operations; (2) graphic arts facilities; (3) flexographic printing plants; and (4) latex monomer production. The characteristics of each of these emissions are discussed along with the catalytic technology used to control these emissions.     

有机废气吸附净化处理的新型工艺研究

简要介绍了挥发性有机废气的来源、分类及其对人体和环境的危害，以及盐城市部分企业近年来的产生和排放状况。较详细地论述了吸附净化处理技术用于废气中挥发性有机化合物的去除和回收研究工艺与特点，阐明了目前有机废气的净化处理方向。     

Models to Estimate Volatile Organic Hazardous Air Pollutant Emissions from Municipal Sewer Systems

Abstract

Emissions from municipal sewers are usually omitted from hazardous air pollutant (HAP) emission inventories. This omission may result from a lack of appreciation for the potential emission impact and/or from inadequate emission estimation procedures. This paper presents an analysis and comparison of the models available to estimate volatile organic HAP (VOHAP) emissions from sewers. Comparisons were made between the different theoretical foundations of the models, as well as between the emissions predicted by the models for a single sewer component. Sewer gas concentrations predicted by the models were also compared to measured sewer gas concentrations reported in the literature. Two of the models were compared in their ability to estimate sewer VOHAP emissions for a large U. S. city using National Pollution Discharge Effluent System data for the influent wastewater to the city's municipal wastewater treatment facilities. This estimate showed that, regardless of the model used, sewer emissions are a potentially significant source of VOHAP emissions in the urban environment. The choice of model, however, is thought to be less critical to sewer emission estimates than the source of sewer wastewater VOHAP concentration data.     

Sources of Volatile Organic Compounds in a University Building

A total of 34 volatile organic compounds (VOCs) were measured in the indoor of laboratories, offices and classrooms of the Chemical Engineering Department of Hacettepe University in Ankara in 2 week-day passive sampling campaigns. The average concentrations ranged from 0.77 to 265 μg m^?3 at the different indoor sites, with the most abundant VOC found to be toluene (119.6 μg m^?3), followed by styrene (21.24 μg m^?3), 2-ethyltoluene (17.11 μg m^?3), n-hexane (10.21 μg m^?3) and benzene (9.42 μg m^?3). According to the factor analysis, the evaporation of solvents used in the laboratories was found to be the dominant source.     

Measuring Concentrations of Volatile Organic Compounds in Vinyl Flooring

ABSTRACT

The initial solid-phase concentration of volatile organic compounds (VOCs) is a key parameter influencing the emission characteristics of many indoor materials. Solid-phase measurements are typically made using solvent extraction or thermal headspace analysis. The high temperatures and chemical solvents associated with these methods can modify the physical structure of polymeric materials and, consequently, affect mass transfer characteristics.

To measure solid-phase concentrations under conditions resembling those in which the material would be installed in an indoor environment, a new technique was developed for measuring VOC concentrations in vinyl flooring (VF) and similar materials. A 0.09-m² section of new VF was punched randomly to produce ~200 0.78-cm² disks. The disks were milled to a powder at -140 °C to simultaneously homogenize the material and reduce the diffusion path length without loss of VOCs. VOCs were extracted from the VF particles at room temperature by fluidized-bed desorption (FBD) and by direct thermal desorption (DTD) at elevated temperatures. The VOCs in the extraction gas from FBD and DTD were collected on sorbent tubes and analyzed by gas chromatog-raphy/mass spectrometry (GC/MS). Seven VOCs emitted by VF were quantified. Concentration measurements by FBD ranged from 5.1 |ig/g VF for n-hexadecane to 130 |Jg/g VF for phenol. Concentrations measured by DTD were higher than concentrations measured by FBD. Differences between FBD and DTD results may be explained using free-volume and dual-mobility sorption theory, but further research is necessary to more completely characterize the complex nature of a diffusant in a polymer matrix.     

Preparation of Activated Carbons from Raw and Biotreated Agricultural Residues for Removal of Volatile Organic Compounds

ABSTRACT

Activated carbons with diverse physical and chemical properties were produced from four agriculture residues, including raw barley husk, biotreated barley husk, rice husk, and pistachio shell. Results showed that with adequate steam activation (30–90 min, 50% H₂O_(g)/50% N₂), activated carbons with surface areas between 360 and 950 m² g^?1 were developed. Further increases in the activation time destroyed the pore structure of activated carbons, which resulted in a decrease in the surface area and pore volume. Biotreated agricultural residues were found to be suitable precursors for producing mesoporous activated carbons. The oxygen content of activated carbons increased with increasing activation time. Results from X-ray photoelectron spectroscopy examination further suggested that H₂O molecules react with the carbon surface, enhancing the deconvoluted peak area of carbonyl and carboxyl groups. Equilibrium adsorption of toluene indicated that the adsorption capacities increased with an increase in the inlet toluene concentration and a decrease in temperature. The adsorption isotherms were successfully fitted with Freundlich, Langmuir, and Dubinin– Radushkevich equations. Activated carbons derived from agricultural residues appear to be more applicable to adsorb volatile organic compounds at a low concentration and high-temperature environment.

IMPLICATIONS This paper presents data on the preparation of activated carbons from agricultural residues, especially the waste from biohydrogen generation. Experimental results indicated that with proper carbonization and steam activation, activated carbons with diverse characteristics can be produced from various agricultural residues. The resulting activated carbons effectively adsorb toluene. This work provides useful information for reutilization of these agricultural residues, helping in decreasing the cost of biological waste treatment and providing a cost-effective alternative to conventional adsorbent production and application.     

Total Volatile Organic Compounds in the Urban Environment of Delhi

ABSTRACT

Total volatile organic compounds (TVOCs) in the urban ambient environment of Delhi were monitored from November 1994 to June 1995 at 13 sites using an inexpensive and a manual-labor-intensive sample collection procedure in want of sophisticated equipment. The results of the study show appreciable levels of TVOCs in the ambient environment of Delhi. The amount of TVOCs in the ambient environment was found to vary between 3 and 42 ppmv and exhibited wide temporal and seasonal variations. On a diurnal cycle, TVOC levels mostly peaked at 9:00 a.m., which coincided with the peak traffic hour. TVOC buildup in the urban atmosphere has serious implications for air quality through the formation of highly toxic oxidants. The results of this preliminary study make out a strong case for a regular monitoring of TVOCs in the urban environment of Delhi.     

Partition of Volatile Organic Compounds in Activated Sludge and Wastewater

Abstract

The Henry’s law constant is important in the gas-liquid mass transfer process. Apparent dimensionless Henry’s law constant, or the gas-liquid partition coefficient (K’ _H), for both hydrophilic (methanol, isopropyl alcohol, and acetone) and hydrophobic (toluene and p-xylene) organic compounds in deionized (DI) water, a wastewater with a maximum total dissolved organic carbon (DOC) content of 700 mg/L, and DI water mixed with a maximum activated sludge suspended solid (SS) concentration of 40,000 mg/L were measured using the single equilibrium technique at 293 K.

Experimental results demonstrate that the K’ _H of any of the test volatile organic compounds varied among three situations. First, the K’_H of the hydrophilic compounds in mixed liquor with the maximum SS concentration was 9–21% higher than those in DI water. Second, those for toluene and p-xylene were 77% and 93% lower, respectively, in the mixed liquor with the maximum SS concentration. Third, the K’_H values of all of the test compounds in the wastewater were only 10% lower than those in DI water.

A model was developed to relate K’ _H with wastewater DOC and the SS concentration in the activated sludge using an organic carbon-water partition coefficient and activated sludge-water partition coefficient as model parameters. The model was verified and model parameters for test compounds estimated.     

An Investigation of Odors and Volatile Organic Compounds Released during Composting

ABSTRACT

The emissions of odors and volatile organic compounds produced from a commercial composting operation have been studied using a laboratory-scale composting system. The composting activity of a typical commercial compost feed was followed by monitoring the composting temperature, as well as the respiratory rate. Using a controlled aeration system, the gaseous volatiles produced were tested for odors using the "dilution-to-threshold" method, as well as gas composition, as determined by gas chromatography-mass spectrometry.

The results indicated that while there may be a reasonable correlation between the release of volatile organic compounds (VOCs) and odors, care has to be taken when trying to identify offensive odors with specific chemical species. However, the data obtained suggests that offensive odors formed during commercial composting may be due to sulfurous and nitrogenous compounds, although their concentrations in the compost gases may not be very high.

The major release of VOCs occurred during the first two weeks of composting, after which the gaseous releases fell dramatically as the composting process proceeded and temperatures started to fall.     

Long-path FTIR Measurements of Volatile Organic Compounds in an Industrial Setting

A long-path Fourier transform spectrometer was used to make measurements of volatile organic compounds in an industrial complex in New Castle, Delaware as part of the Superfund Innovative Technology Evaluation (SITE) program. These data are compared to data taken with a whole-air canister technique. To provide an effective comparison the canisters were transported along the path for a 32-min period. For each FTIR spectrum, 256 interferograms were co-added over a 4-mln period. Eight individual spectra were then co-added to obtain the comparison data.